Depression and Risk Factors for Low Back Pain

Abstract

DEPRESSION AND RISK FACTORS FOR LOW BACK PAIN Abstract Although low back pain has been widely studied, our understanding of risk factors, as well as the impact of comorbidities on low back pain, remains limited. The broad aim of this thesis was to investigate the association between low back pain and common risk factors, namely symptoms of depression, sleep problems, and physical activity, by conducting a series of studies. Four studies (Chapters Two to Five) were carried out to explore the relationship between low back pain and symptoms of depression. Taken together, the results of these studies suggest that a causal relationship between low back pain and symptoms of depression is weak, at best. The influence of symptoms of depression to the risk of low back pain is more complex than previously thought, and likely to be dependent on people’s genetic susceptibility. Additionally, the findings suggest that symptoms of depression have a negative impact on the prognosis of low back pain. Chapter Six investigated the association between low back pain and sleep problems and the results showed that, to some extent, there is an overlap in the set of genes affecting both sleep quality and low back pain. Lastly, this thesis described the protocol (Chapter Seven) and preliminary results (Chapter Eight) of the feasibility investigation for the AUTBACK study – a study that investigates the effects of physical activity on low back pain. The employment of a twin design to investigate the effects of physical activity for low back pain has proven to be feasible in terms of follow-up rate and completeness of data. This approach is promising and opens a new frontier for the consideration of the genetic effects on the relationship between physical activity and low back pain. The findings of the studies reported in this thesis have advanced our understanding of the relationship between low back pain and commonly reported risk factors such as depression, sleep, and physical activity.